The nature of the neurological and cerebrovascular deficits in cocaine abusers and whether they persist in abstinence is unclear. Blood flow velocity of the anterior and middle cerebral arteries was measured by transcranial Doppler sonography in cocaine abusers (n = 50) and control subjects (n = 25). Blood flow velocity was measured within 3 days and again after about 28 days after being admitted to an inpatient research ward to determine whether blood flow velocity improved during monitored abstinence conditions. The mean, systolic, and diastolic velocities as well as the pulsatility index in middle and anterior cerebral arteries significantly differed between controls and cocaine abusers (p < .05). Cerebrovascular resistance is increased in cocaine abusers and the increase persists for over a month of abstinence. Further research is needed to determine whether cerebrovascular resistance can be improved by pharmacological manipulations and whether improved blood flow relates to improved treatment outcome. - Drug Abuse, Neuropsychological Testing, Psychological Evaluations, Blood Flow, Cocaine - Human Subjects: Interview, Questionaires, or Surveys Only